Generally, lightweight aggregates are widely used in a concrete for increasing weight of a high-building, a bridge and so on, insulating and waterproof materials for building roof and layer, a concrete for dampproof, a soundproofing portioning, building materials for preventing vibration, materials for controlling moisture of a golf green, gardening materials of a flowerpot and a plant for controlling moisture evaporation, ceramic filters, and ceramic carrier.
Up to the present, natural aggregates as the lightweight aggregates collected from a river, mountain and sea and so on are mostly used. However, it is urgent for us to supply the artificially lightweight aggregates on account of the exhaustion of the natural aggregates.
In the meantime, during the fabrication of the concrete, since the aggregates are suitably filled in order to obtain a superior strength, it is important to produce the aggregates below 2 mm in grain size. In conventional artificially lightweight aggregates, a forming body of 5-12 mm is injected in the type of a horizontal firing and then, it is fired and discharged.
However, it has difficulty in manufacturing artificially lightweight aggregates or artificially lightweight sands below 4 mm in size owing to the adhesion phenomenon between the aggregates during the firing process of high temperature. That is, the artificially lightweight aggregates or artificially lightweight sands below 4 mm in size pass through a sintering process of 1150-1200° C. among the fabrication processes. At this time, in case of containing solvent ingredients of a product in abundance, since fluids are formed at the surface thereof, the adhesion phenomenon between the aggregates is generated, so that it has difficulty in manufacturing the artificially lightweight aggregates or the artificially lightweight sands below 4 mm in the general furnace or a rotary kiln.